The present invention relates generally to an electrical connector or penetrator and, more particularly, to such a connector or penetrator which is capable of withstanding very high pressures.
The term "electrical connector" utilized throughout this specification is intended to include electrical penetrators and other forms of electrical interconnecting devices. An electrical connector of the type to which the present invention relates generally comprises a metal shell which is installed into a pressure withstanding bulkhead, wall or underwater hull structure. Electrical conductors are mounted in the shell by glass, glass-ceramic, or ceramic insulators which are sealed in the shell. There may be individual insulators for each conductor in the form of individual glass ring seals or beads, such as disclosed in U.S. Pat. Nos. 3,735,024; 3,750,088 and 3,780,204. Alternatively, a single insulator may be utilized in the shell with multiple holes receiving the conductors, such as disclosed in U.S. Pat. Nos. 3,998,515 and 4,088,381. The conductors are normal double-ended pin contacts. Plug connectors having socket contacts in them can be mated on one or both sides of the electrical connector containing the sealed pin contacts.
Normally the conductors are sealed in the electrical connector shell by a compression type seal. The coefficient of thermal expansion of the metal shell is higher than the glass, resulting in high compressive stresses in the glass during the cooling cycle during the glass sealing operation. These high compressive stresses result in excellent sealing characteristics. However, the differences in thermal coefficient of expansion of the glass and metal cause longitudinal stresses in the glass seals. These stresses increase as the length-to-diameter ratio of the glass bead increases, resulting in shearing and cracking of the glass. Preferably the foregoing ratio should not exceed four, otherwise fracturing of the glass seal may occur. For example, in a moderately dense contact arrangement layout (208 contacts in a connector layout diameter of 4.5 inches), if the glass bead diameter is about 0.200 inches, the length of the bead should not exceed 0.75 inches. Such connector is capable of withstanding pressures up to 2,000 psi. This pressure capability could be increased by using a connector shell which has a thicker metal web, using individual beads which are relatively short. However, in such an arrangement electrical problems are encountered because of plating salts and/or other contaminants becoming entrapped in the contact passages in the metal web during the manufacturing process of the connector.
It is the object of the present invention to provide an electrical connector which is capable of withstanding considerably higher pressures than the prior art connectors, yet does not encounter the electrical problem which is mentioned above resulting from contaminants being entrapped in contact passages in the connector header.